fix: add ESM entrypoint

Author: jviide

.changeset/short-areas-act.md

@@ -0,0 +1,5 @@
+---
+"sorted-queue": patch
+---
+
+fix: add ESM entrypoint

src/index.esm.mts

@@ -0,0 +1 @@
+export * from "./index.js";